John Niesen and his mother, Mary Riley, on Thursday filed the lawsuit in U.S. District Court in Tampa, saying police officers violated his brother's civil rights and caused his death. Subsequently, the lawsuit says, the city has continued a conspiracy by destroying evidence and not conducting a thorough investigation. It also says the alleged cover-up has prevented John Niesen from getting the names of all the officers involved.

The suit, which does not specify a dollar figure, asks for damages that cover "loss of support and services, loss of companionship, past mental pain and suffering and future mental pain and suffering."

Niesen has long claimed that his 18-year-old brother, Michael, was killed in July 1977 by police who were distraught over the death of a fellow officer thrown from the truck his brother was driving.

In the suit, he alleges that for 31 years, a number of officers participated in a conspiracy to conceal the events of that night.

Mahony, while citing Niesen for reckless driving, learned the truck was reported stolen. As the rookie officer approached the truck, Niesen accelerated, and Mahony jumped into the truck's bed. Niesen fishtailed several times before the truck flipped along Memorial Causeway, killing Mahony.

The Niesen family maintains Michael was alive, resting against a palm tree while medical crews tried to save Mahony. Later, when it looked like the officer wasn't going to live, then-officers Michael Egger, Mark Cairns, Edward Garner, James Gravely and Charles Butler formed a tight circle around the teen and beat him with their nightsticks. He died hours later.

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Niesen initially sued in April 2007, but a month later withdrew the suit, saying he needed more time.

On Thursday, he sounded optimistic he would eventually get a jury trial.

"It's a crying shame that I couldn't get these people to do their job and this is what it's come to," said Niesen, 53, who has retired from the security business. "They can sit and say what they want to say, but (the evidence) has been given to them over and over again.

"I would, for once in 31 years, like to hear a real ... response," added Niesen, who says he's spent at least $1-million investigating his brother's death. "They have sat on their laurels and accused me of being delusional and out of my mind, but I challenge them to produce the documentation that they did anything."

City Attorney Pam Akin declined to comment until she's seen the lawsuit.

The Police Department said in a statement that "to this day, there has been no evidence of criminal conduct on the part of law enforcement officials regarding the death of Michael Niesen. Over the past three decades, the Clearwater Police Department has consistently encouraged anyone with evidence of official misconduct to come forward so that it may be thoroughly investigated."

Niesen says he initially sued because he was fed up that state and local agencies wouldn't investigate his claims. He said they based their investigations on the original 1977 Clearwater police investigation, which he says was falsified.

His first stab at legal action came on the heels of a March 2007 decision by the U.S. Attorney's Office that said the statute of limitations had expired. The office indicated it didn't view the incident as a first-degree murder or conspiracy — two areas where the statute would not apply.

Tampa-based Matthew Wilson, one of four attorneys representing Niesen, said statute of limitations hasn't started running because the "defendants are still continuing to deny the Niesen family the ability to sue for the wrongful death ... the officers who murdered his brother."

However, James Yacavone, representing most of the officers in the suit, said "if you have a reasonable inkling that you've been wronged . . . then you have a certain amount of time to sue or you lose your right of action."

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The case had been reviewed repeatedly by Clearwater police, the State Attorney's Office and the Florida Department of Law Enforcement.

Each time, investigators said they found no new evidence to reopen it.

Last year, a St. Petersburg Times review of Pinellas-Pasco State Attorney's Office and Florida Department of Law Enforcement files showed that more than a dozen state officials formally reviewed the incident at least six times over the years, interviewing more than 20 witnesses, reviewing records and poring over transcripts.

John Niesen also has investigated the case, supplying reams of files to investigators. But some of the testimony from witnesses conflicted with that found by state investigators. Investigators felt one witness, a former paramedic at the crash scene, was not telling the truth when he took a lie detector test.

Another, Edward Garner, a former police officer at the scene who is named as a defendant, said he was coached about what to include in his report. He was later fired for drinking on the job, has an extensive criminal history and served in prison for DUI-manslaughter.

Legal experts who spoke with the Times in recent months agree the Niesen family has a tough case to prove. However, they say, unlike a criminal case where guilt must be proved beyond a reasonable doubt, a civil case turns on which side can put forth the more credible evidence.

Niesen on Thursday sounded confident he'd win.

"Maybe when it's all done we'll have a clear, concise story of what happened," he said. "That's all I've ever asked for, but nothing they do will ever bring Michael back."